Terminal for resistance members and method of producing same.



L. REICHOLD. TERMINAL FOR RESISTANCE MEMBERS AND METHOD OF PRODUCING SAME.

APPLICATION FILED DEC. 5,1914.

Patented Mar. 6, 1917.

Inventor Ludwig Relchold *Hns Attorn e3 Witnesses; m\\@ w! mmms Fsrsns CO.PNOTOLIINQJVASHINGTDN. o c.

A 'enrrnn s'rArEs PATENT anion.

LUDWIG REICHOLD, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

TERMINAL FOR RESISTANCE MEMBERS AND METHOD OF PRODUCING SAME.

To all w/iomz't may concern:

Be it known that I, Lnnwro REIGHOLD, a subject ofthe German Emperor, residing at Pittsfield, in the county of Berkshire, State of Massachusetts, have invented certain new and useful Improvements in Terminals for Resistance Members and Methods of Pro ducing Same, of which the following is a specification.

My invention has reference to a method of forming terminals on sheathed wire, and to a heating device provided wit-h terminals secured to the sheathed wire in accordance with this method.

My invention relates to electric heating devices and the like, and has particular reference to the formation of terminals for connecting such devices to electric circuits. In the manufacture of the heating devices it is common to use as a heating element a resistance conductor of the type known as sheathed wire, and my invention is particularly useful in connection with such heating elements, although not necessarily limited in this respect.

The manufacture of sheathed wire suitable for use in connection with my invention is described in United States Letters Patent No. 1,107,233,which was granted to Chester Moore on August 11th, 1914, to which reference is hereby made for'the details of such manufacture. Briefly, however, it may be said that such wire is formed from an ingot comprising a core or resistance wire inclosed in a metal sheath, the space between the sheath and the resistance element being thoroughly packed with an electric insulating, heat conducting, powdered material, such as magnesia. The ingot is swaged or otherwise worked down to the required diameter.

The ends of the resistance element of sheathed wire are not suitable for directly receiving connections leading to the supply circuit, since the resistance element itself is of very small diameter, and it is not mechanically strong enough for this purpose. It is necessary, therefore, to electrically connect to the ends of the resistance element, terminals which are rugged enough for such connection. In practice, it has been found difiicult, however, to satisfactorily secure such terminals to the ends of the resistance element. It is not feasible to solder Specification of Letters Patent.

Application filed December 5, 1914.

or braze the terminals to the core wire without the use of a flux, such as boraX, for the reason that the parts, particularly the core wire, are damaged by excessive oxidation, and when a flux is used to prevent oxidation, crystallization of the core wire and other defects frequently develop in service which unduly shorten the life of the heating unit.

In accordance with my invention, the terminals are molecularly secured to the core wire by disposing the end of the terminal adjacent the end of the resistance element, usually in the presence of a suitable brazing or soldering material such as copper or silver, and without any flux, and within a cap or housing from which the atmosphere is excluded, and then applying sullicient heat without the cap to melt the soldering or brazing material.

My invention finds its most useful application, however, in the manufacture of heating devices in which metal is cast directly around the sheathed wire to form a heating body. Then thus made, the heat of the molten cast material is utilized to secure the terminal to the core wire.

For a fuller understanding of my invention, reference may be had to the accompanying drawing, in which Figure 1 is a plan view of a flat-iron embodying my invention; Fig. 2 is a longitudinal section through the same; Fig. 3 is a detail view showing the terminals disposed adjacent to the end of the resistance element of the sheathed wire before the two have been secured together, and before they have been inclosed by the housing; Fig. 4 is a similar view showing the terminals molecularly secured to the ends of the resistance elements of the sheathed wire and with the top of the housing cut 0H and removed; Fig. 5 is a view similar to Fig. 4:, but showing terminal pins secured to the ends of the resistance elements of the sheathed wire, which are adapted to receive the sockets of a plug switch in a well understood manner; and Fig. 6 is a cross section of the sheathed wire.

Referring now to the drawings, 1 is the sheathed wire with which my invention is particularly intended to be used, and which may be coiled or otherwise arranged, as indicated in Figs. 1 and 2, before the metal of the heating device is cast around the same. The resistance element of the sheathed wire is represented by the reference numeral 1, the metal sheath by 1 and the compacted insulating material by 1. A metal cap 2 is secured to the ends of the sheathed wire,

and is preferably formed of two telescoping sections 8 and at, the ends of the sheathed wire projecting through the bottom part of the bottom section 3. The ends of the resistance element of the sheathed wire, which are bared, as indicated in Fig. 3, are received in metal bushings 5, which serve as retainers for the materials, as more fully hereinafter described, located within the cap, and the bushings are in turn surrounded by suitable refractory insulating material 6. The insulating material may be held in position by crimping the upper edge of the lower section 3 of the cap over a shoulder formed at the upper portion of the insulating material, as indicated at at. (See Fig. 3). The ends of the metallic terminals 7, which, in the form here shown, are intended for permanent connection to the supply conductors, are placed within the bushings 5 adjacent the ends of the resistance elements of the sheathed wire, and with pieces of soldering or brazing material 8, such as copper or silver. Now, when sufficient heat is applied outside of the cap, the soldering or brazing material melts and molecularly secures the terminals to the ends of the resistance elements, and as the oxygen of the air is excluded during the operation, the parts are not damaged by oxidation. In practice it is found that the small amount of oxygen which fills the cap before the process is begun is not sutlicient to damage the parts, and it is probable that during the operation this oxygen disappears altogether.

lVhile the heat necessary to melt the solder or brazing material may be applied in any desired manner, as by a torch, 1 pre fer, when possible, to utilize the heat of the molten material which is cast around the sheathed wire and around the lower portion of the cap to form the body of the heating device, as indicated at 9 in the, drawing. For this purpose the sheathed wire and the lower portion of the cap are, of course, placed in the mold, and the molten material cast directly .around the same. Suitable handle supports 10 are secured to the iron. After the casting operation is complete, the top of the cap is out off, as indicated at 11 in Figs. 1 and 4, and the terminals, which may be coiled up in order that they may be housed in the cap, are then straightened out, and may be secured to suitable conductors. The terminals shown in Figs. 1 to i are intended for permanent connection to supply conductors.

In Fig. 5, I have shown the terminals in the form of p'ms'which are adapted to receive the Socket of a plug switch in a well known manner. These terminals may conveniently be formed as continuations of the steel bushings within which the brazing or soldering operation takes place.

l/Vhile I have shown my invention embodied in a fiat-iron, it will, of course, be understood that it is applicable to any kind of heating or other device in which sheathed wire is utilized.

. In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

lVhat I claim as new and desire to secure by Letters Patent of the United States, is

1. The method of molecularly securing a terminal to the end of a resistance element, which consists in disposing the end of the terminal adjacent the end of the resistance element in the presence of other metal and without the use of a flux, inclosing them in substantially air-tight housing, and applying heat to the housing suiiicient to melt said metal.

2. The method of electrically connecting a terminal to the resistance element of sheathed wire, which consists in disposing the end of the terminal adjacent to the end of the resistance element in the presence of other metal and without the use of a flux, casting metal about the sheathed wire and utilizing the heat of the casting to melt said metal and thereby molecularly secure said terminal directly to said resistance element.

3. The method of electrically connecting a terminal to the resistance element of sheathed wire, which consists in placing a terminal adjacent the end. of the resistance element, casting metal about the sheathed wire to form a heating member, excluding the atmosphere therefrom, and utilizing the heat of the casting to molecularly secure the terminal to the resistance element.

4. The method of making a heating device provided with sheathed wire and a metal body, which consists in placing the end of a terminal and the end of the resistance element of the sheathed wire adjacent each other in the presence of other metal, forming a substantially air-tight housing over the same, and casting meta-l about the sheathed wire and one end of the housing.

5. The method of making a heating device provided with sheathed wire and a metal body, which consists in placing the end of a terminal adjacent the end of the resistance element in the presence of other metal, inclosing the same in a substantially air-tight housing, casting metal about the sheathed Wire and the end of the housing to form a heating body, and removing the other end of he housing to expose the terminal.

6. The method of making a heating device provided With sheathed Wire as a heating element and metal heating body, Which consists in reflexing or coiling a portion of a terminal and disposing one end thereof adjacent that of the bared end of the resistance element in a suitable retainer, inclosing the retainer and terminal in a substantially airtight housing, casting metal around the sheathed Wire and one end of the housing, removing the other end of the housing to eX- pose the terminal, and bringing the terminal outside of the housing.

7 A heating device comprising a heating element composed of'sheathed Wire, a metal cup surrounding the ends of the sheathed Wire, terminals electrically connected to the ends of the sheathed Wire Within said cup, and a body of metal cast around said sheathed Wire and cup.

8. A heating device comprising a heating element composed of sheathed Wire, a metal cup surrounding the ends of the sheathed Wire, retainers located Within and insulated from said cup for the reception of the ends of the resistance elements of the sheathed Wire, terminals electrically connected to the ends of the resistance elements Within said retainers, and a body of metal cast around said sheathed Wire and said cup.

In Witness whereof, I have hereunto set my hand this third day of Dec., 1914.

LUDWIG REIOHOLD.

Witnesses:

A. K. NUGENT, G. F. XVRIGHT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

